Fig. 3. LC-MS/MS traces of in vitro ketoreduction and dehydration reactions. Overnight incubation conducted with KR substrates 4 (panel A) and 5 (panel B) and TylDH3-KR3 in the presence of NADPH. The identity of the β-hydroxy products (shown in blue) was confirmed by co-injection with authentic standards. Incubation with synthetic 7 (panel C) and 9 (panel D) resulted in sole formation of dehydration products 10 and 11 (trace shown in red), respectively. Panels A and C blue trace represents MRM (m/z 340 → 184) and red trace represents MRM (m/z 300 → 181). Panels B and D blue trace represents MRM (m/z 368 → 212) red trace represents MRM (m/z 328 → 151).